1. Field of the Invention
The present invention relates to a display apparatus and a display method thereof. More specifically, the present invention relates to a method for improving color non-uniformity and luminance non-uniformity.
2. Description of the Related Art
As methods for correcting color non-uniformity of a display apparatus, there is known a method, as disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) No. HEI10-84551 (Japanese Patent No. 3202613), for correcting the color non-uniformity by dividing a display screen into blocks, making the divided blocks uniform in luminance level, and thereby correcting the color non-uniformity that occurs to the display screen.
There is also known a method, as disclosed in JP-A No. HEI9-200571, for increasing a correction amount large at a low luminance compared to at a high luminance at which the input video signal level is high, using a gain adjustment circuit and a DC offset adjustment circuit.
The method disclosed in JP-A No. HEI10-84551 has, however, the following disadvantage. The luminance of the entire display screen is made uniform by reducing the luminance of the high luminance part according to the low luminance part. As a result, a maximum luminance of the display screen is reduced.
JP-A No. HEI9-200571 discloses that the luminance non-uniformity and the color non-uniformity are corrected by making the luminance uniform as done by so-called shading correction, and that it suffices that the correction amount at the high luminance is small since the luminance non-uniformity and the color non-uniformity are less conspicuous at the high luminance.
However, at the high luminance, it is true that the luminance non-uniformity is less conspicuous but the color non-uniformity is still conspicuous. Due to this, if the correction amount is simply set small at the high luminance as disclosed in JP-A No. HEI9-200571, it is impossible to improve image quality degradation resulting from the color non-uniformity.
On the other hand, demand for increasing the luminance of the display screen of a display apparatus, particularly a projection display apparatus (projector) rises so as to improve visibility at a bright location. Demand for reducing the color non-uniformity and the luminance non-uniformity also rises following an increase in a size of the display screen. As stated above, it is conventionally difficult to realize both an increase in the luminance of the display screen and a reduction in the color non-uniformity and the luminance non-uniformity.